But the OP didn't suggest breaking the encryption, but to run a traffic analysis, which includes things such as identifying the realworld identities of people s

But the OP didn't suggest breaking the encryption, but to run a traffic analysis, which includes things such as identifying the realworld identities of people sending encrypted email, determing who those people are communicating with (both for their encrypted and unencrypted emails), and other ways of extracting information from messages without needing to actually break the encryption. Once you've carried out this analysis, you know on who you can apply the more realworld techniques that you suggest.